1. Field of the Invention
The present invention relates to a method and an apparatus for dissolving and isolating carbon dioxide gas, which is discharged in large quantity from stationary generating sources such as thermoelectric power plants, under the sea for preservation of global environmental conditions, and in particular to a method and an apparatus for dissolving and isolating carbon dioxide gas by dissolving the carbon dioxide gas into seawater at shallow sea level and by isolating it at deep sea level after it is sinked by gravity current.
2. Description of the Prior Art
In the past, for isolating carbon dioxide under the sea, the following methods have been adopted: (a) liquid carbon dioxide is directly discharged at deep sea level of 1000 m or deeper under the sea level; (b) carbon dioxide is isolated by directly dumping dry ice at deep sea level; or (c) carbon dioxide gas is discharged and dissolved in seawater at shallow level under the sea (200 to 400 m under sea level). In short, carbon dioxide gas has been discharged directly into the seawater in the past.
In the above methods (a) and (b), carbon dioxide can be isolated at deep sea level by avoiding the disposal in the water area with high biological density, while vast amount of energy is required for liquefying carbon dioxide, for transporting liquefied carbon dioxide, and for dumping liquefied carbon dioxide. For example, when total quantity of the carbon dioxide discharged from the sources such as thermoelectric power plants are disposed by the above methods (a) and (b), energy consumption will be by 40 to 50% higher than the energy currently consumed for this purpose.
On the other hand, by the method (c), it is possible to maintain the energy consumption to the level only by 10 to 20% higher than the current level. However, if renewing rate of the seawater at the blowing outlet of the carbon dioxide gas is low, dissolving efficiency is extremely low. Also, the problems such as acidification of the water area with high biological density and the secondary environmental problems caused by such acidification are unavoidable.
Further, all of the above methods (a), (b) and (c) are disadvantageous in that all of the pressure energy of the liquid carbon dioxide or carbon dioxide gas must be abandoned to the sea.
As described above, we must admit that all of the methods currently adopted have grave drawbacks in terms of energy and environmental problems.